For an uplink channel of 3rd generation partnership project long term evolution (3GPP LTE), a data signal of each terminal is assigned to contiguous frequency bands to reduce the cubic metric (CM) and the peak-to-average power ratio (PAPR). Transmission using these contiguous frequency bands may be called “contiguous frequency transmission.”
A terminal transmits data according to a frequency resource assignment information reported by a base station. Frequency resource assignment information for contiguous frequency transmission involves two information about a start position and an end position (or a bandwidth from a start position) in a transmission band. Therefore, when the system bandwidth is expressed as NRB [RB], the number of signaling bits of frequency resource assignment information can be represented by equation 1 below. That is, because the number of candidates for a start position and an end position in a transmission band can be expressed as NRB (the numbers of both ends and borders between adjacent two RBs in a frequency band)+1, signaling bits are required for the numbers of combinations to select two candidates for a start position and an end position in the frequency band out of the number of candidates NRB+1, in equation 1.
                    [        1        ]                                                                      The          ⁢                                          ⁢          number          ⁢                                                            ⁢                                                          ⁢          of          ⁢                                          ⁢          signaling          ⁢                                                            ⁢                                                          ⁢          bits                =                              ⌈                                          log                2                            ⁢                              (                                                      N                    RB                                    +                  1                                            ⁢                              C                2                            )                        ⌉                    ⁢                                          [          bits          ]                                    (                  Equation          ⁢                                          ⁢          1                )            
where a resource block (RB) is a unit for assigning frequency to data. One RB is formed with 12 subcarriers. When NRB=100 [RB] is satisfied, the number of signaling bits is 13 [bits].
For an uplink channel of LTE-Advanced, which is an evolved version of 3rd generation partnership project long-term evolution (3GPP LTE), using “non-contiguous frequency transmission” in addition to contiguous frequency transmission is under consideration to improve the sector throughput performance (see Non-Patent Literature 1).
Non-contiguous frequency transmission is a method of transmitting a data signal and a reference signal by assigning such signals to non-contiguous frequency bands, which are dispersed in a wide range of band. As shown in FIG. 1, in non-contiguous frequency transmission, it is possible to assign a data signal and a reference signal to discrete frequency bands. Therefore, in non-contiguous frequency transmission, compared to contiguous frequency transmission, the flexibility in assigning a data signal and a reference signal to frequency bands in each terminal increases. By this means, it is possible to gain greater frequency scheduling effects.
Here, as a method of reporting frequency resource assignment information for non-contiguous frequency transmission, there is a method of reporting whether or not to perform assignment for each RB in the system band, using a bitmap (see Non-Patent Literature 2). As shown in FIG. 2, a base station reports whether or not to assign the resource per predetermined frequency assignment unit [RB] (per 4 [RB] in FIG. 2), using one bit. That is, a base station reports to a terminal to which frequency is assigned, a frequency assigning bit sequence that is obtained by assigning the bit value of 1 to the former and assigning the bit value of 0 to the latter of the assignment sub-band that is assigned to a terminal to which frequency is assigned and the non-assignment sub-band that is not assigned, in a plurality of sub-bands that are formed by dividing the system band per frequency assignment unit [RB]. In FIG. 2, the frequency assignment unit to which bit “1” is assigned is a frequency area that is assigned to a terminal to be assigned while the frequency assignment unit to which bit “0” is assigned is a frequency area that is not assigned to the terminal to be assigned. Therefore, when expressing a system bandwidth as NRB [RB] and a frequency assignment unit as P [RB], the number of signaling bits required for the frequency resource assignment information of this method can be represented by equation 2 below.[2]The number of signaling bits=┌NRB/P┐[bits]  (Equation 2)